Combating air pollution

The end of World War II heralded an era of population growth throughout the nation and especially in the State of California, where many returning soldiers and their families settled. With population growth came the expansion of urban areas, the shrinking of agricultural lands and the availability and affordability of automobiles. The term “smog,” originally coined to describe the combination of smoke and fog prevalent in London, soon became a household word in the Bay Area, with open fire dumps and wrecking yards burning 24 hours a day. The first step at controlling the area’s air pollution came in 1955, when the state set up a nine county Bay Area Air Pollution Control District — the first regional air pollution control agency in the country.

In October 1969, Livermore Laboratory Director Mike May announced the formation of a new committee, headed by Carroll Maninger, to study the smog issue and suggest ways in which the Lab’s scientific expertise and technical resources might be able to help. Congressional changes to the Atomic Energy Commission (AEC) Act in the late 1960s gave the AEC the authority to assist others on health and safety problems, including environmental pollution issues, unconnected with AEC’s atomic energy charter.

In announcing the new study, May stated: “Over the past several years a number of people at LRL have considered whether the Laboratory could and should help with the problem of air pollution, and if so, what projects could be accomplished…We must survey what the Laboratory can best do in the light of work going on elsewhere…and how the Livermore Laboratory can contribute to the overall national effort in solving the air pollution problem.”

In March 1972, a proposal from the Lab’s Air Pollution Prevention Committee, now the Environmental Studies section of the Director’s Office, was accepted by the U.S. Department of Transportation, and a $1.3 million contract was awarded to the Lab to develop a numerical model to assess the global climate impact of future fleets of high-altitude aircraft, including supersonic transports (SSTs). United States decision makers needed information on the potential effects of the proposed SST fleet, as concerns had been raised that exhaust emissions might chemically react in ways that would thin the stratospheric ozone layer.

Under the guidance of the Environmental Studies Group, Livermore’s Mike MacCracken and others led the work on the project, drawing on advanced computer modeling techniques developed at the Lab during the past decade. MacCracken and a small group in the Theoretical Physics Division were building upon pioneering work done by the Lab’s Cecil “Chuck” Leith, who in the late 1950s developed the first global general circulation model, which was able to simulate the behavior of large weather systems.

Livermore’s one-dimensional model of stratospheric ozone, developed under Julius Chang, was one of the first simulation tools in the world used to examine ozone interactions with the SST’s nitrogen oxide emissions. While the SST fleet never came to fruition primarily for economic reasons, the Lab’s calculations, along with work done by others, were a contributing factor to the outcome.

In July 1972, the Lab formally brought together such efforts when it formed the Atmospheric Sciences Group (G Group) in the Physics Department, under Joseph Knox. Working closely with the Environmental Studies Group, G Group focused on several disciplines including using “simulation techniques and computer modeling to interpret trends in background levels of various pollutants as a step toward developing a world-wide pollutant monitoring program.”

In 1973, while SST studies were still ongoing, the Laboratory received another grant, from the National Science Foundation, to develop a model for environmentally sound land-use planning in the Bay Area. Working with the Bay Area Air Pollution Control District (BAAPCD) and NASA Ames Research Center, G Group’s MacCracken and Knox, under the guidance of the Environmental Studies Group, headed up the Lab’s effort to develop a regional photochemical computer simulation of the San Francisco Bay Area. Photochemical reactions had been discovered in 1950 to be responsible for the formation of smog’s primary ingredient: ground level ozone.

By 1975, the Lab’s effort in this study resulted in two regional air quality computer simulation models: the Livermore Regional Air Quality (LIRAQ) models, LIRAQ-1 and LIRAQ-2. Using local topography, meteorology and pollutant-source inventory as input data, these models were able to calculate the time and space variation of pollutant concentrations in fixed grid cells. Results from these models, and later versions, served as the basis for preparing the Bay Area’s Air Quality Maintenance Plan, which eventually lowered the number of days of excess ozone from around 50 per year to one or two days a year.

In the mid-1970s, when the effects of chlorofluorocarbon (CFC) emissions on stratospheric ozone became an issue, the Laboratory was at the forefront of modeling efforts, thanks to the computational and chemical tools developed at the Lab in the early 1970s. In response, Don Wuebbles of G Division developed a two-dimensional model that predicted increasingly severe ozone depletion from continued use of CFCs in refrigerators, air conditioners and aerosol spray cans. The research team later developed a technique for calculating ozone depletion potential (ODP) of other compounds, a formulation that was included in the 1987 Montreal Protocol, which set goals for globally phasing out the use of halocarbons with high ODP.

In 1989, W. Lawrence Gates and fellow atmospheric scientists at the Laboratory formed a new group called the Program for Climate Model Diagnosis and Intercomparison (PCMDI) — a program designed to improve the quality of models for predicting potential climate change. Livermore quickly became an internationally recognized institution for climate model analysis, and LLNL’s atmospheric scientists at PCMDI continue to play key roles in international work studying climate change.

Pictured: W. Lawrence Gates, the chief scientist and first leader of LLNL’s PCMDI.